July 7 (Day 188) - Why didn't the chicken cross the road?

Internet kicks back in - hooray!

10 prairie chickens per square mile. This is a number that I wish I had known before I made the trip to Wray.  I will explain.

Looking at eBird, I can see that there are lots of Greater prairie-chickens sightings in and around Wray, CO. However 99% of the recorded sightings are from the lek season that runs from late March to early May.  A lek is the method through which many species of grouse select mates each spring. Basically, grouse converge on specific sites where male birds strut their stuff and where female birds select mates based on these displays. Each species of grouse has peculiarities unto itself, but the displays that males put on are spectacular across the board.  The beauty of leks from a birding standpoint is that they happen like clockwork in the exact same spots each year. Observing displaying birds on lek is as simple as showing up – literally. The mating rituals are incredibly odd and intoxicatingly beautiful. I have attached a few videos of mating displays so folks unfamiliar with these behaviors can get an idea of how cool they are. This is why there are no sightings outside of lek season; No one bothers to look for these birds off-lek. After the lek breaks-up, individual birds disperse into the surrounding habitat to nest and raise young. During this time they can be incredibly hard to find.  A lek may have upwards of 40 birds in one spot, but after the birds disperse, their density drops, as estimated for prairie-chickens around Wray, to that 10 birds per square mile as referenced above. I will return to this number in a bit, so stay tuned!

Greater prairie-chicken lek

Greater sage-grouse lek

Here is a photo of the area that I birded today.

What you can see is that there is lots of high grass that makes spotting birds on the ground all but impossible. I figured that if I were to make enough passes through this type of habitat on my bike, I might be able to flush a bird and see it in flight. This is the strategy I employed this morning. I had been pointed to CR (that’s County Road) 45 as a good starting point. I had passed over this road yesterday during the heat of the day, so I knew the road was passable and what to expect habitat and terrain-wise. I wanted to get there before sunrise which meant a 3:30am wake-up (after an 11pm bedtime, UGH). I arrived at the spot at 4:45am for 5:30am sunrise. I immediately heard Ring-necked pheasant for year bird #496. I heard lots of these over the course of the morning, but I was unable to grab a view of one. I’m sure I’ll get on at some point. I spent the morning riding this and several other county dirt roads with zero success on the Prairie-chicken front. It started to get really hot at 11am, so I shut it down, rode back to town, ate a whole pizza at 7-11, checked back into my hotel room since I would need another day to find the bird, and immediately passed out for the next 3 hours.

Today's wanderings - I rode the stretch along

Route 385 4 times!

I woke up and put in a call to a local rancher about the birds. He is the largest landowner in the area, and he was nice enough to grant me permission to roam where I wanted on his lands. He is somewhat of a local expert on these birds as many of the big tour companies visit his lands to see the Prairie-chickens during lek season. It was he who quoted me the 10 birds per square mile figure. Given that there are several leks of 30-40 birds a piece in this area, and these are spaced a few miles apart, this 10 birds per mile after dispersal sounds totally reasonable to me. Just for fun, let’s unpack this number a bit.

A square mile is 27,878,400 square feet (5280 x 5280).

This means there is ~1 bird in approximately 2,787,840 square feet of suitable habitat.

I figure that if I walk through the grass, I need to be @25 feet from a bird to flush it. Given how long the grass is, there is little to no chance I will be able to see a bird on the ground where I expect it to be. I arrived this 25 feet based on the fact that I needed to be 10 feet from the Dusky grouse to see it move, 25 feet from Montezuma quail to flush it, and 40 feet from the Gunnison sage-grouse to flush those.

To make the math friendly, let’s just assume I need to be 26 feet from a bird to flush it. This means that at any point, I have a 52-foot flush radius from me. If I were to walk 1 mile in the grass, I would effectively cover 52 x 5280 or 274,560 square feet of habitat.

So, for every mile I walk in suitable habitat, I have a ~10% chance of flushing a bird (274,560 square feet covered divided by 2,787,840 square feet per bird = 0.1 birds). This is the calculation I was doing in my head as I dismounted my bike and began my afternoon foray into the sage with the permission of the rancher. 

I walked around for 2 hours without seeing a hint of a Prairie-chicken. I had set 8pm as a hard departure time. I arrived back at my bike at 7:20pm after covering what I estimated was 4 miles of habitat. At this stage I was beat. The birding spot was ~14 miles from my motel , and I had already traversed this and additional distance 3 times today. I would still have to cover it once more to return as the sun set in another 1.5 hours. I knew I had the morning tomorrow to search for the birds, so I decided to shut it down for the night. Then I remembered my mantra of using every minute in good habitat. I decided to make one more pass through a bit more habitat that I had not yet covered. BANG!!! I flushed a single bird at 7:40! I got a brief but serviceable look at my 17^th life bird of the year and bird #497 for 2014! I was not able to get a photo, but even I am going to miss some! It flew up and over a hill about 100 yards away. I trotted over the hill, but was not able to find the bird visually. I started clapping my hands and BANG – the bird went up again about 50 feet from me this time. I again got a fair look, but then it was gone for good. I would have loved a longer look at a sitting bird, but I guess I'll have to come back during lek season to get it! When all is said and done I will have pushed over 300 miles on the bike into this one bird! Sometimes the odds don't mean a thing; This bird was shear determination. 

Pawnee > Sterling - 65 miles
Sterling > Wray - 97 miles
Wray birding - 74 miles
Wray > Sterling - 86 miles (return trip less b/c I took birding detour on outgoing trip

Total for this bird: 322 miles!

Oh, and for those that were wondering. The distance at which I originally flushed the bird? 25-30 feet, just as I predicted!  Given that I walked less than 5 miles total, today’s find was a very lucky one. Yeah, the distance biked in suitable habitat heped raise my total chances, but I still cannot actually believe I found this bird today.

Lastly, the donation match has been extended through to today so today is the LAST day! If you have been thinking about donating but haven't done so yet, please do consider donating now. Victor Emanuel Nature Tours (VENT) is matching the first $2500. With the match I am really hoping this will put me over the $20,000 mark. Remember, 100% of donations go to bird conservation. The birds thank you for your support!!!

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